BU Mars Rover Team - Rover Work & Club Promotion

Since my freshmen year at BU, I have been part of the BU Mars Rover Team's Mobility-Chassis Team. Our team is currently manufacturing and developing our rover "ROSS" according to the standards set by the University Rover Challenger (URC).

**UPDATE FOR MARCH 2025. Please find our very first video submission of our completed rover below. :)

Design Roles in Club

My work on the Mechanical Sub-Team revolved around designing the wheel-axle system, making sure that martian terrain traversals can be optimized, and that the wheels can support both the weight of the remaining parts of the rover and the electrical power provided by the 12-V DC motors that will attach individually to each of the six wheels. I performed structural analysis tests on our wheels and designed them by using SolidWorks and its Finite Element Analysis (FEA) features.

Other things I contributed to the team alongside other members include applying a stress analysis to optimize the most efficient mass-weight ratio that will help us reduce the 70kg weight restriction as imposed by the URC, and constructing the mount for our DC motors that will reduce the moment due to the weight of the motor, therefore optimizing motor torque needed for the terrain traversal. A more detailed description of the current motors being utilized is describe later in this article.

We also use SolidWorks' motion study and FEA tests to observe movement simulations in order to determine the bodies' interactions and reactions due to changes in the surface and figure out the strengths and weaknesses of each concurrent design relative to itself and the rest of the rover.

Pictured below are models of my current wheel design:

Figure 1: Current Design of the Wheel: Side Not Facing the Rover. (Updated 03/20/2025)

From this angle, the wheel and front end of the rim can be seen. The rim is attached from the front to the shaft, which will allow for the rover's robust movement capabilities when attached to the suspension, as shown with this wheel's attachment to a sample bogie leg. The motor's shaft is held in place by a series hub. A motor casing holds said motor in place when attached to the suspension while also protecting it from potential damage. Additionally, the wheel's various curved treads allow for better traction during movement.

Figure 2: Current Final Design of the wheel. Side facing the Rover. (Updated 03/20/2025)

This side once again highlights the wheel, providing a better look at the back end of the rim holding the other side of the wheel in place, as well as the motor encapsulating the brushless DC motor and the bogie leg. The motor cover is connected to the bogie suspension with hex head cap screws. It extends to the back, providing extra protection for the motor as well as the wires that will connect it to the central electrical generator that will be installed within the chassis. And below is what our rim looks like:

Figure 3: Current Design of the Rim: (Updated 03/20/2025)

FEA Analysis

Various FEA Static tests were done to simulation how parts would act while undergoing certain effects. This picture showcases a FEA result of the outer wheel undergoing a normal force of 300 lb:

Figure 4: Sample FEA Simulation of Current Outer Wheel Design (Updated 03/20/2025)

This result shows off the net von Mises stress across the wheel, or the overall stress as it undergoes deformation due to the normal force.

The color scale on the right follows the idea that lower stress values are represented by cooler colors like blue, while higher stress values are represented by hotter colors like red or yellow.

In the case of this wheel, the vast blue shown implies that there is a balanced transfer of energy between the treads and interior of the rim. Identical net results were demonstrated when we applied a centrifugal force about the center rather than a normal force about the treads.

Material Selection

As of now, our outer wheel will be 3D Printed using thermoplastic polyurethane (TPU) due to both its flexibility and durability, and the rims as well as the motor case will be made out of aluminum because it is lightweight, and also good strength and durability.

The motor our wheels will be utilizing is the GoBILDA Yellow Jacket Planetary Gear Motor shown below:

Figure 4: Current Motor for our wheels: (Updated 01/10/2023)

This GoBILDA motor contains a pre-built-in gear head that sets its overall RPM to approximately 223 RPM. It has a default gear ratio of 9:1 which will provide us with sufficient torque and acceleration for each wheel. When accommodating for the wheel's approximate diameter of 150 mm, as well as its gear ratio formula of ~26.85 on GoBILDA's website, we use the following formula to estimate our top vehicle speed:

Vehicle Speed = Wheels RPM × Tire diameter × π × (60 / 63360),

Where the tire diameter is represented in inches, π is the circle constant that represents the ration between the tire's perimeter and diameter, 60 is the number of minutes in an hour and 63360 is the number of inches in a mile.

Using the numbers we know, and converting 150 mm to ~5.906 inches:

Vehicle Speed = 223 RPM x 5.906 in. x π x (60 / 63360)

= ~3.92 mph

Therefore, our rover currently has an approximate top speed of ~4 mph. Because we are not accounting for the extra weight that remains to be placed on the rover from remaining equipment and tools, from life detection gear to the robotic arm, we can assume that this speed will drop a bit.

Major Update: Rover in Action: First Working Test

As of March 2025, I am proud to showcase our first successful test run of the rover, demonstrating its mobility and suspension system functionality!! Check out the videos below:

Video 1: The BUMRC's first ever Systsem Acceptance Rover (SAR), for the 2025 URC

In 2025, after I left the BUMRC, the team successfully completed our first ever System Acceptance Review (SAR) and submitted our first working test video of the rover. Although we didn’t advance to the final round of that year's University Rover Challenge (URC), the experience of making this video and designing the rover into how it is now provided us with valuable insights that we’re excited to apply as we refine our design for future competitions.

Video 1: Motion Test of the Rover featuring several of our members. Video taken 02/08/2025

E-Board Positions and Responsibilities

During my sophomore year at BU, I was promoted to the Outreach Chair position as well as the head of the Project Management Team for the 2022-2023 school year. With these two positions, I lead and direct member engagement through networking, projects, and events, as well as coordinate outreach programs locally and plan guest speaker conferences. Some of our past works include raising money through Mochi Donut fundraisers, and partnering with Northeastern University's NURover team in November 2022 to collaborate with each other and get together while discussing ideas about our rovers at a sufficient level. We also work to promote our club's work from membership growth through Boston University's SPLASH Club Fairs to showing off the built of our rover on our social media pages.

At the end of my junior year, I was elected Vice President of the BU Mars Rover Club for the 2023-2024 school year. I will be leading club recruitment, aiding with administrative affairs with the department of Electrical and Computer Engineering (ECE) and collaboration with our esteemed sponsors at Raytheon. Raytheon was generous enough to support and sponsor our club and has contributed a substantial donation to our club, and offered their experts to provide valuable advice and insights on the Rover project. I will also continue to support additional duties as needed, especially as I continue to maintain my role as Outreach Chair.